First time snowboarder needs advise?

My Boyfriend asked me to go on a snowboarding trip in December with him, and instead of sitting in front of the fireplace in the lodge lobby I want to join in on the fun. Can anyone give me some tips? I also need help with board and boot sizing. I am 5'5 and about 130-140 pounds I've tried looking at sizing guides and charts but no two sites give me the same answer. Some say 148, 149 and others say 150 or 151 I am totally lost..Someone help?..